Autism spectrum disorders (ASD) are highly heritable complex neurodevelopmental disorders of the brain, which cannot be explained by mutation or mutations in any single gene. In the last couple of years linkage and association studies have led to the identification of several mutations that confer susceptibility to ASDs. Studying the functional effects of these mutations offers a unique window to a better understanding of the underlying neurobiology. One of the major obstacles is the difficulty in obtaining neurons and glial cells from patients with an ASD. The goal of this project is to develop the methods to convert skin cells from patients with ASDs into neurons and to characterize these neurons using high content screens. To achieve this goal we will convert fibroblasts into pluripotent progenitor (iPS) cells. In the next step we will differentiate these iPS cells into neurons in vitro. Finally we will study the specific cell- intrinsic aspects of neuronal function that are likely to be disrupted in ASDs including synapse formation, axonal and dendritic morphology and calcium signaling. We have already established all of these techniques in our laboratory. Before we can apply these techniques on a larger scale we need to first address some of their limitations. The focus of R21 phase of the proposal is to improve and standardize the methodology. We will first generate and characterize iPS cells from human fibroblasts harvested from healthy controls and ASD patients with mutations in the CACNA1C and SHANK3 gene, mutations known to affect neuronal development, and optimize and characterize the differentiation of iPS cells (Specific Aim 1). We will develop standardized protocols for differentiating iPS cells into mixed populations of cortical, dopaminergic, and inhibitory neurons (Specific Aim 2). We will then characterize the cellular phenotypes of neurons from ASD and from controls, focusing on calcium signaling, dendritic arborization, and cell survival (Specific Aim 3). In the R33 phase of the project we will target a larger number of individuals with ASD a known to have a mutation in others gene/s affecting neuronal development (Specific Aim 4 and 5).